The following patents and patent applications are believed to reflect the state of the art:
EP 1400903 of Sony United Kingdom Ltd.;
EP 1424640 of Sony United Kingdom Ltd.;
EP 1494144 of Sony United Kingdom Ltd.;
EP 1538838 of Sony Corp.;
EP 1906317 of Sony United Kingdom Ltd.;
U.S. Pat. No. 5,778,362 to Deerwester;
US 2003/0233566 of Gutta, et al.;
US 2004/0003401 of Gutta, et al.;
WO 02/25938 of Koninklijke Philips Electronics N.V.;
WO 2004/047446 of Koninklijke Philips Electronics N.V.;
WO 2007/026357 of NDS Ltd.;
WO 2008/102331 of NDS Ltd.; and
WO 2008/051882 of Music-Strands, Inc.